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Biomedical subjects

S G Baker

Publications and source records attributed to S G Baker.

At least 55 records · Page 3Linked to original sources
PubMed1987

Prevalence of hypercholesterolaemia in young Afrikaners undergoing coronary artery bypass surgery. Ischaemic heart disease risk factors.

Ischaemic heart disease risk factors, with particular reference to familial hypercholesterolaemia, were studied in 47 male and 6 female Afrikaners, aged 55 years and under, admitted to hospital for coronary bypass surgery. The outstanding feature in this group with severe coronary atherosclerosis demonstrated angiographically was that about half had severe hypercholesterolaemia (greater than or equal to 8.5 mmol/l), and that of the severely hypercholesterolaemic patients about half again had familial hypercholesterolaemia (FH). This yielded an overall prevalence of FH in the 53 cases of 1 in 4 (26.7%) and strongly supports the contention that FH is a major risk factor for severe coronary artery disease in young Afrikaners. The only other risk factor of importance was cigarette smoking, about 80% of the patients being current or ex-smokers.

Angina, Unstable↗
PubMed1987

Prevalence of hypercholesterolaemia in young Afrikaners with myocardial infarction. Ischaemic heart disease risk factors.

Ischaemic heart disease (IHD) risk factors, with particular reference to familial hypercholesterolaemia (FH), were studied in 39 male and 12 female Afrikaners aged 55 years or under in an intensive care unit immediately after an acute myocardial infarction and in the survivors at about 3 months after the infarct. Two major risk factors were found. Firstly, about three-quarters of both male and female patients smoked more than 15 cigarettes daily. Secondly, 51% of males and 37% of females had serum cholesterol values of greater than or equal to 7.0 mmol/l and about 20% of both men and women had levels of greater than or equal to 8.5 mmol/l. Three male and 2 female patients--1:10 of the whole sample--had FH diagnosed by rigorous criteria, a prevalence similar to the figure of 1:8 predicted from the frequency of FH heterozygotes in the Afrikaans-speaking population. None of the other IHD risk factors such as hypertension, diabetes and hyperuricaemia appeared to be important. The role of obesity appeared to be indirect by virtue of its frequent association with and possible contribution to hypercholesterolaemia. Many of the patients had a history of previous IHD episodes.

Adult↗
PubMed1986

Familial hypercholesterolaemia--the need for adequate counselling and family tracing.

A search for the founder member(s) responsible for the familial hypercholesterolaemia (FH) gene(s) in the RSA inadvertently revealed the existence of a marriage which links two pedigrees in which FH occurs. This marriage could result in the birth of an FH homozygote child. The couple concerned should have--but had not--been informed of the implications of their union before their marriage. The importance of identifying individuals at risk through extensive tracing of families in which FH occurs and the relevance of subsequent counselling are illustrated.

Child↗
PubMed1986

Clonidine and the hormonal responses to graded exercise in healthy subjects.

The aim of this study was to assess the acute effects of clonidine, an alpha 2-adrenergic agonist, on hormonal responses to graded exercise in 8 healthy young men. After fasting overnight, each subject was tested on 2 mornings, 1 week apart. On one occasion he was given 200 micrograms clonidine orally and on the other identical placebo tablets, the order being randomized in a double-blind fashion over the 2 days. Thereafter each subject performed 2 successive treadmill runs, equivalent to 60 and 100%, respectively, of maximal aerobic power. Clonidine pretreatment blunted the maximal increase in plasma catecholamines by more than 60% of the control response (p less than 0.01), without significantly altering the rise of plasma cortisol or ACTH. Furthermore, clonidine significantly reduced the exercise-induced maximal rise in plasma glucose, without modifying the slight decline in mean plasma insulin or increase in pancreatic glucagon levels. The drug did not affect the maximal increments in plasma growth hormone or prolactin occurring after exercise. It was concluded that a single dose of clonidine suppressed peripheral sympathetic responses, without altering central (pituitary) alpha-adrenergic-mediated hormonal responses, to short-term exercise in healthy men.

Adrenocorticotropic Hormone↗
PubMed1986

Risk reduction for nonmelanoma skin cancer with childhood sunscreen use.

Exposure to ultraviolet radiation is the principle cause of basal and squamous cell carcinomas of the skin, which are the most frequent tumors occurring in white residents of the United States. Using a mathematical model based on epidemiologic data, we quantified the potential benefits of using a sunscreen with a sun protective factor of 15 and estimate that regular use of such a sunscreen during the first 18 years of life would reduce the lifetime incidence of these tumors by 78%. Additional benefits of sunscreen use during childhood include reduced risk of sunburn, retarding the pace of skin aging, and possible reduction in melanoma risk. We recommend that pediatricians encourage sunscreen use and sun avoidance as a regular part of pediatric preventive health care.

Adolescent↗
PubMed1985

Hormonal and biochemical responses to transcendental meditation.

This study was designed to assess whether transcendental meditation (TM) could influence various endocrine responses in 10 experienced male meditators. Nine matched subjects, uninformed of the TM procedure, acted as controls. Meditators successfully practised their technique for 40 min in the morning while controls relaxed for this period. No significant differences emerged between these 2 groups with respect to carbohydrate metabolism (plasma glucose, insulin and pancreatic glucagon concentrations), pituitary hormones (growth hormone and prolactin) or the 'stress' hormones, cortisol and total catecholamines-although meditators tended to have higher mean catecholamine levels. Plasma free fatty acids were significantly elevated in meditators 40 min after completing the period of TM. No clear evidence was thus obtained that any of the stress, or stress-related, hormones were suppressed during or after meditation in the particular setting examined.

Adult↗
PubMed1984

Association between familial hypercholesterolaemia and church affiliation. Is this the result of sociocultural isolation of migrant farmers in 19th-century South Africa?

The family trees of 57 Afrikaans -speaking familial hypercholesterolaemia (FH) index cases were traced to look for founder surnames, for an association between FH and affiliation to the Gereformeerde Kerk (GK), and for consanguinity. Two possible founder surnames were identified. Each occurred in more than 5% of individuals and both were well known among the founders of the GK. Affiliation to the GK was much more common in our sample (45% of 994 individuals) than in the general population (5%), an overall odds ratio of 7,38. This association was stronger in older generations. There were 21 consanguineous marriages, the two suspected founder surnames and affiliation to the GK featuring prominently among them.

Consanguinity↗
PubMed1984

Alcohol-potentiated reactive hypoglycaemia depends on the nature of the carbohydrate ingested at the same time.

Alcohol may provoke reactive hypoglycaemia when drunk with a sucrose mixer (gin and tonic) but not in the form of a starch-based beverage. In the present study alcohol-potentiated reactive hypoglycaemia was shown to depend on the nature of the carbohydrate ingested together with the alcohol. When 14 men (9 normal weight and 5 obese) aged between 20 and 50 years consumed a 50 g glucose load together with 50 g ethanol over an hour, their early plasma insulin response was significantly higher and their later fall in plasma glucose significantly lower than after drinking the same amount of a starch solution (maize meal) and alcohol. In four subjects (3 of them non-obese) plasma glucose concentrations dropped below 2.8 mmol/l after drinking the glucose-alcohol solution. Obesity seemed to be associated with features of peripheral insulin resistance. We conclude that the common social custom of drinking alcohol together with a simple sugar mixer should probably be modified.

Adult↗
PubMed1983

The effect of low-dose aspirin and platelet aggregation in familial hypercholesterolaemia.

Since the platelets of patients with familial hypercholesterolaemia (FH) are hyperaggregable, the inhibitory effect of low-dose aspirin on platelet aggregation in response to adenosine diphosphate, collagen, adrenaline and arachidonic acid was tested in 9 young adult patients with FH and compared with that in 9 normal subjects. After a single oral dose (150 mg) of aspirin the degree of inhibition of platelet aggregation was the same in the two groups, as was the recovery time (in days) for full restoration of platelet aggregation . In a second experiment in which 162 mg aspirin was administered daily for 28 days, inhibition of platelet aggregation was sustainable in both the patient and the control groups. These results suggest that despite the recognized hyperaggregability of platelets from patients with FH, daily low-dose aspirin ingestion effectively inhibits their in vitro aggregation and may therefore prove beneficial as supplemental therapy to reduce the rate of myocardial infarction in this high-risk group.

Adult↗
PubMed1982

Effect of drinking bottled beer on plasma insulin and glucose responses in normal subjects.

Alcohol may provoke reactive hypoglycaemia when drunk with a sucrose mixer ('gin and tonic') but does not do so when taken in the form of a starch-based beverage like sorghum beer. We examined the hypoglycaemic potential of bottled beer (Lion Lager; South African Breweries), which differs from sorghum beer in that it contains less carbohydrate (polysaccharides and simple sugars) and has a higher alcohol content. After an overnight fast 5 Black men each drank 2 litres of Lion Lager over an hour. Over the ensuing 5 hours their plasma insulin, glucose and alcohol concentrations were compared with the responses previously documented before and after consuming the same volume of sorghum beer or a 100 g control carbohydrate solution. Bottled beer elicited a prompt but short-lived rise in plasma insulin (mean +/- SEM, 37 +/- 7 mU/l at 1 hour), which was significantly greater than that produced by sorghum beer but less sustained than after drinking the control carbohydrate solution. After drinking bottled beer plasma glucose levels fell to a mean nadir of 3,6 mmol/l at 2 hours (compared with 5,4 mmol/l for sorghum beer), thereafter slowly returning to the basal value, while a substantial rise in the blood alcohol concentration occurred. We conclude that the development of alcohol-induced reactive hypoglycaemia is largely determined by the nature of the carbohydrate ingested together with alcohol.

Adult↗
PubMed1982

Treatment of homozygous familial hypercholesterolaemia with probucol.

Ten patients with homozygous familial hypercholesterolaemia were treated with the recently introduced drug probucol (Lurselle; Mer-National) for 15-21 months. Xanthomas regressed or disappeared in most patients, angina lessened in two-thirds of cases and the ECG improved in half of those with pretreatment abnormalities. The mean fall in serum total cholesterol levels after 18 months of therapy was 27%. High-density lipoprotein cholesterol levels fell transiently in the early months of therapy but then returned to the pretreatment range. Plasma probucol levels varied between 20 micrograms/ml and 90 micrograms/ml, indicating good compliance, but did not correlate with the clinical or hypocholesterolaemic responses. Probucol was well tolerated by child and adult patients. The effects of probucol in this therapeutically resistant disorder were better than expected. Considered in relation to efficacy, safety, tolerance and convenience probucol appears to be the most satisfactory treatment for homozygous familial hypercholesterolaemia currently available.

Adolescent↗
PubMed1982

Platelet function in familial hypercholesterolaemia in South Africa and the effects of probucol.

Patients with Familial Hyperlipoproteinaemia Type II showed evidence of increased platelet aggregability when compared to normal controls. This abnormality was not influenced by oral therapy with probucol whether or not the serum cholesterol levels were lowered during the study period. Probucol assays indicated adequate compliance during the study period but did not demonstrate any uptake of the drug by platelets. In vitro studies also failed to demonstrate any inhibition of platelet function at therapeutic drug levels although higher levels were inhibitory.

Adolescent↗
PubMed1982

Treatment of homozygous familial hypercholesterolaemia with portacaval shunt.

Thirteen patients with homozygous familial hypercholesterolaemia (HFH) were treated with portacaval shunt operations. One patient died postoperatively and the others were followed for 2-6 years. The main beneficial effects were regression of xanthomas and sustained falls in serum total and LDL cholesterol levels of about 18% in the majority of cases, sustained rises in HDL cholesterol values in most patients, and the long period of survival after the operation without further deaths or serious cardiac complications. Other favourable effects were improvement of angina pectoris, ejection systolic múrmurs or electrocardiograms in some cases. Growth and development of patients after the operation were normal and there were no clinical or biochemical signs of liver damage or portal systemic encephalopathy. Apart from the patient who died, negative or adverse effects of the operation included shunt closure causing portal hypertension and bleeding varices in 1 case, unsatisfactory clinical responses in half the patients, small or unsustained falls in serum total cholesterol in one third of cases, and failure of total cholesterol to fall below 12.0 mmol/l in any patient. Enlargement of the spleen appeared to be an invariable consequence of the operation and possible reasons for this are discussed. Finally the place of portacaval shunts in the management of HFH is reviewed.

Adolescent↗
PubMed1980

A host of hypercholesterolaemic homozygotes in South Africa.

From 1972 to 1979 34 patients with homozygous familial hypercholesterolaemia were seen in one clinic in Johannesburg. All were Afrikaners and most lived in Transvaal Province. Their epidemiological, genetic, clinical, and biochemical characteristics were studied. The course of the disease varied considerably among the 34 patients, with no fewer than six surviving into their fourth or fifth decades. In some patients arterial atheroma was severe while cutaneotendinous xanthomas were slight and vice versa. Coronary heart disease was common but peripheral and cerebral arterial disease was rare. Another prominent finding was high concentrations of low-density lipoprotein cholesterol coupled with low high-density lipoprotein cholesterol values. The prevalences of homozygotes and heterozygotes with familial hypercholesterolaemia in Transvaal Afrikaners, calculated from this group of patients, were 1 in 30,000 and 1 in 100 respectively. These figures are the highest ever reported and may help to explain why South African whites have the highest death rate from coronary heart disease in the Western world.

Adolescent↗